FR3065344A1 - HIGH POWER PROJECTOR WITH SOURCE LIGHT LASER DEPORTEE - Google Patents

Abstract

A projector comprising a laser light source (12) and a projection engine (14) having at the input of an integrating tunnel (148) in which the laser light source is remotely connected to the projection motor through a beam of optical fibers (16) having an input and an output, the input of the optical fiber bundle being disposed at an output focal plane of the laser light source and the optical fiber bundle output being brought into contact with the tunnel integrator via a homogenizer plate (20).

Description

Field of the invention

The present invention relates to the field of lighting and it relates more particularly to video / cinema projectors or theater or show light projectors comprising a laser light source allowing high lighting power.

Prior art

Until a few years ago, show light projectors were conventionally made up of an incandescent lamp or a discharge lamp such as Xenon, Mercury, HMI or HTI, and a reflector to direct the light beam from from this lamp to an optical system comprising one or more lenses arranged one behind the other in the light beam.

Recently, projectors whose light sources, intended to replace these discharge or incandescent lamps, are LEDs or laser diodes have appeared on the lighting market, in particular cinema and digital video. when a large lighting power is targeted (typically light intensities greater than 10,000 lumens). These laser light sources are essentially divided into two types: so-called Phosphorus sources and so-called RGB sources.

The phosphor sources are powered by blue laser diodes (430 - 450 nm approximately) and include a phosphor wheel to reconstitute the red and green colors. Their focal plane (generally included in a range of 4000 to 5000 microns) currently does not allow to group several individual modules (today each limited to powers of the order of 10000 to 18000 lumens) in one except to use mirror returns which cause significant power losses. In addition, the phosphor sources must be close to the projection engine (the video head comprising the light modulator) and the association of several individual phosphor sources therefore involves bulky, heavy and noisy assemblies.

The RGB sources are powered by blue, green and red diodes. It is also easy to focus the beams of several RGB diodes at a single point, the focal plane of the order of 300 to 1000 microns making it possible to collect the output light in a single fiber of the same diameter. By combining several fibers into a single bundle or “bundle”, it is thus possible to generate substantial powers. However, this technique is restrictive and particularly expensive, in particular because of the current monobloc construction of the projectors.

These reasons mean that to date projectors, video / cinema or light powered by phosphor laser light sources, are all limited in power.

Object and definition of the invention

The present invention proposes to overcome this constraint with a projector making it possible to deliver a large lighting power, typically from 25,000 to 60,000 lumens or equivalent to discharge lamps from 4 to 6 KW (Type HMI - Xenon) . Another object of the invention is to be able to implement such a projector from any type of light source.

These aims are achieved by a projector comprising a laser light source and a projection motor provided at the input with an integrating tunnel, characterized in that the laser light source is connected remotely to the projection motor through a optical fiber bundle having an input and an output and in that said optical fiber bundle input is arranged at a focal plane of output of the laser light source and said optical fiber bundle output is brought into contact with the integrating tunnel via a homogenization plate.

Thus, by placing a bundle of optical fibers in the focal plane of the laser light source, it becomes possible to use any type of source, and in particular a phosphorus source.

Preferably, the laser light source comprises a plurality of laser light sources and the optical fiber bundle comprises a same plurality of optical fiber bundle inputs which are merged into a single optical fiber bundle output.

By merging these fibers, it is then possible without difficulty to obtain a large lighting power.

Advantageously, the different optical fiber bundle inputs each have a circular section and the single optical fiber bundle output has a rectangular section.

Preferably, the circular section has a diameter greater than the diameter of the focal plane of exit of the laser light source considered and the rectangular section has a length equal to or less than an entry section of the integrating tunnel.

Advantageously, the bundle of optical fibers comprises several thousand to several tens of thousands of optical fibers of standard diameter between 100 and 200 microns.

Preferably, the homogenization plate has a diffusion angle of between 2 and 10 °.

Advantageously, the homogenization plate is fixed on a support integral with the projection engine and sandwiched between the exit of the bundle of optical fibers and the entry of the integrating tunnel.

Preferably, the laser light source is of the RGB or phosphor type and the projection engine comprises one of the following light modulators: DMD matrix, LCD matrix, tri-LCD matrices, Tri-DMD matrices, Lcos matrix and D- matrix. HE HAS.

Brief description of the drawings

The characteristics and advantages of the present invention will emerge more clearly from the following description, given by way of non-limiting illustration, with reference to the appended drawings in which:

FIG. 1 is a block diagram of a projector with a remote light source according to the invention,

FIG. 2 is a detailed view of a bundle of optical fibers î deporting the laser light sources of the projection engine,

FIGS. 2A and 2B are end views of a single inlet and outlet of the bundle of optical fibers of FIG. 2, and

- Figure 3 illustrates the attachment of a homogenization plate relaying the single output of the bundle of optical fibers at the input of the projection engine.

Detailed description of a preferred embodiment

The invention is based on the principle of separating the laser light source, whether of phosphor or RGB type, from the projection engine by a bundle (or bundle) of optical fibers formed from several hundred to several thousand small standard optical fibers. (100/200 microns) and offering a large numerical aperture (0.37 and beyond), the beam entry diameter being adapted to the focal plane of the laser light source used (at least 4 mm for a phosphor light source for example) and this beam preferably being of very long length (up to several hundred meters) in order to allow the ventilation noise of the laser light sources to be offset.

The coupling of several light sources of small powers makes it possible to achieve light intensities equal to or even greater than

000 lumens for video / cinema projectors, or optical powers equal to or greater than 4 to 6 kW for light projectors.

By thus combining several standard optical fibers into a bundle of fibers, it becomes possible to reach fiber diameters which are impossible to obtain with a single fiber (the single fibers have diameters of 1500 microns maximum) and to combine a wide range of length. wave in the visible (420 - 640 nm).

However, a simple grouping of standard optical fibers does not make it possible to optimize the yield due to the thickness of the sheaths which leaves gaps between the fibers causing a consequent loss of yield. Also, the invention proposes to merge these fibers into a single output bundle having an outlet section suitable for the inlet section of the condenser (or integrating rod) of the projection engine and, by inserting a single diffuser / homogenizer between these two parts, to optimize the power delivered and the yield obtained. By fiber fusion is meant a grouping of several silica fibers in a single bundle. The bundles of silica fibers are fused at each end in order to eliminate the inter-fiber spaces, without using glues, or other types of material whose inherent properties are limiting, while retaining the numerical opening of the fibers. The bundles thus fused generally increase the transmission by 50% and are used in applications with temperatures up to 1500 ° C.

Figure 1 illustrates a headlamp structure according to the present invention. This projector 10 is formed of three parts: one or more laser light sources 12, a projection engine 14 and a fused bundle of optical fibers 16 to transport white light from the light source to the projection engine thus removed from the source.

The laser light source 12 can be a phosphor light source of the type sold by the company Digital Projection UK and delivering at the output a beam of white light at a determined focal point. It may also be an RGB laser light source as described in application W02016 / 113490 or application WO2016 / 156759, both filed in the name of the applicant and making it possible to concentrate different light beams from RGB diodes at a determined focal point at the output of this laser light source.

The projection engine 14 is conventionally organized around a light modulator 140, a prism 142 and an optical unit 144 comprising in particular projection lenses 146 forming the objective of the projector. The light modulator is conventionally a DMD (digital micromirror device) matrix, but other configurations can also be used such as an LCD, Lcos or D-ILA matrix and tri-LCD or tri-DMD matrices. Whatever the configuration chosen, an integrating tunnel or rod 148 is always present at the entry of the optical path to ensure better alignment and spatial uniformity as in the lamp systems of the prior art.

The fused bundle of optical fibers 16 illustrated in more detail in FIG. 2 allows the coupling of one or more laser light sources according to the power requirements.

In particular, the number of inputs 16A, 16B, 16C, 16D of the beam depends on the total power desired and that of each of the phosphor or RGB laser light sources. For example, an RGB laser light source of the type described in the aforementioned application WO2016 / 156759 delivering an optical power of 20 to 40W (or even more) per RGB color will make it possible to obtain a projection power of 60 to 120W or more by input, or output of powers from 240 to 480W and more.

The beam entry diameter (see FIG. 2A) depends on the type of laser light source used, therefore on the dimensions of the focal plane. Thus, at least an entry diameter of 6 mm will be chosen for a phosphor laser light source whose focal plane is at least between 4 and 5 mm. This inlet diameter will define the number of fibers required from several hundred (i.e. approximately 400 fibers of 200 microns for a diameter of 4 mm) to several thousand (i.e. approximately 3,500 fibers of 100 microns for a diameter of 6 mm) for a diameter of standard unitary fiber of 100 to 200 microns for example.

Similarly, the size of the output beam 16E depends on the total number of fused unit fibers (14,000 fibers in the example with four inputs immediately preceding) and on the section of the integrating tunnel 148. Finally, to increase the performance, the shape of the output beam is adapted to that of the projection matrix (DMD chip for example) and therefore preferably with a rectangular section (see FIG. 2B) proportional to that of the matrix and of length equal to or less than the section of the integrating tunnel. However, an oval / elliptical section or any type of geometric shape, as soon as the widest diameter is equal to or less than the section of the integrating tunnel, is also possible.

At the outlet of the fused fiber is arranged a homogenization plate 20 intended to ensure a perfect distribution of colors as well as a perfect distribution of light. It should be noted that this homogenization plate is not intended to make “coherent” the coherent light coming from the of the fused fiber, this divergence being ensured downstream through the prism of the projection engine, but to allow a uniform spread of the light flux on the projection surface (95% center / periphery of the projection surface).

As shown in FIG. 3, the homogenization plate advantageously fixed on a support 150 secured to the projection engine is sandwiched between the exit of the fused fiber 16E and the entry of the integrating tunnel 148. For the optimization of the light output, it must have a diffusion angle of between 2 ° and 10 ° at the entrance to the integrating tunnel and must be able to accept a divergence angle of the fused fiber from 6 ° to 15 °. Such a homogenization plate is available for example from the company Holo-OR Ltd under the reference RH-215-I-Y-A.

The configuration also obtained is simple with yields from 60 to 75% higher than those of the devices of the prior art while presenting particularly reduced costs. It is subject to little stress, only alignment in the axis of the integrating tunnel being required and still with a fairly flexible tolerance. Note also that this arrangement makes it possible to physically shorten the length of this integrating tunnel.

Claims (10)

1. Projector comprising a laser light source (12) and a projection motor (14) provided at the inlet with an integrating tunnel (148), characterized in that the laser light source is connected remotely to the projection motor through a fiber optic bundle (16) having at least one input and one output and in that said at least one fiber optic bundle input is arranged at at least one focal plane of output from the source laser light and said fiber optic beam output is brought into contact with the integrating tunnel via a homogenization plate (20). 2. Projector according to claim 1, characterized in that the laser light source comprises a plurality of laser light sources and the optical fiber bundle has the same plurality of optical fiber bundle inputs (16A, 16B, 16C, 16D) which are merged into a single fiber optic bundle output (16E). 3. Projector according to claim 2, characterized in that the different fiber optic beam inputs each have a circular section and the single fiber optic beam output has a rectangular section. 4. Projector according to claim 3, characterized in that the circular section has a diameter greater than the diameter of the focal plane of the output of the laser light source considered. 5. Projector according to claim 3, characterized in that the rectangular section has a length equal to or less than an inlet section of the integrating tunnel. 6. Projector according to any one of claims 1 to 5, characterized in that the optical fiber bundle (16) comprises several thousand to several tens of thousands of optical fibers of standard diameter between 100 and 200 microns. 7. Projector according to claim 1, characterized in that the homogenization plate (20) has a diffusion angle between 2 and 10 °. 8. Projector according to claim 7, characterized in that the homogenization plate is fixed on a support (150) integral with the projection engine and sandwiched between the exit of the bundle of optical fibers (16E) and the entry of the integrating tunnel (148). 9. Lighting projector according to any one of claims 1 to 8, characterized in that the laser light source is of the RGB or phosphor type. 10. Projector according to any one of claims 1 to 9, characterized in that the projection engine comprises one of the following light modulators: DMD matrix, LCD matrix, triLCD matrices, Tri-DMD matrices, Lcos matrix and matrix D-ILA.